What Causes You to Sweat? Hidrosis and Hyperhidrosis

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Reviewed on 5/5/2017

What Is Sweat?

On one hand, we all know it when we feel it. Sweating (also called perspiration) is that damp feeling on our skin when it’s hot outside, or when we have been working hard. We’ve all felt it many times.

On the other hand, there’s a lot about sweating you probably don’t know yet. Did you know everyone has between 2 million and 4 million sweat glands? Do you know why waiting for a job interview makes your palms slick? Did you know that even when you’re unaware of it, your body is sweating just a little?

In this article, learn some of the many causes of sweating, from hot flashes to falling in love. You’ll also discover a condition known as hyperhidrosis—excessive sweating—along with health tips for treating it. So find a cool, well-ventilated place and read on for more on the steamy causes of perspiration.

Heat

Probably the best-known cause of sweating is heat. Any time the thermometer soars you know you’ll be battling huge temperatures, and your first line of defense against heat is sweat. Sweat’s entire purpose is to keep our warm-blooded bodies from overheating. The scientific term for this is “thermoregulation.”

The key to sweat’s cooling power is evaporation. Evaporation is what happens when a liquid becomes a gas. In this case, the sweat from your skin evaporates into the air around you. Sweat needs some of the heat from your body in order to change from a liquid to a gas. That’s called heat transfer. And that’s basically why you cool down when you sweat—the sweat carries off some of your body temperature as it evaporates.

That also helps explain why sweating doesn’t work as well when the air around us is humid. On humid days, the air is already full of moisture. That means your perspiration has more difficulty escaping your skin. And that’s why more humid weather feels hotter to us, even if the overall temperature is cooler than in drier weather.

Under normal circumstances, you can sweat out a maximum of 1.5 liters every hour—a little over six cups. But in very hot, humid places like jungles, that changes. You can adapt after a few weeks in such conditions to sweat out as much as 3.5 liters per hour—almost a gallon!

It should be fairly clear why it’s so important to your health to drink water when you’re sweating that intensely. Not only do you need water for all kinds of other purposes, but running out of perspiration when you need it can be hazardous to your health. You only need to lose about 2 percent of your body fluid before signs of heat exhaustion set in. And if your core temperature rises above 103 degrees, that can be fatal.

Getting Angry

When you get really, intensely, fuming mad, the last thing on your mind is probably sweat. But it’s there for everyone to see. Anger triggers your stress response, also known as “fight or flight.” Hormones are released, causing your heart rate to quicken, your breathing to deepen, and you begin to drip with perspiration.

Everyone gets angry sometimes. But for some, anger is an ongoing problem. There are some treatments you can use to help better manage your anger. One treatment involves realizing what makes you angry. Pay attention to what it feels like when you’re angry. Do you get tense? Do you get a headache? Do you snap at others or yell? Keep a journal and refer back to it to discover what has been making you cross. When you do get angry, give yourself time in a quiet place to breathe deeply and work through your feelings. Tell people around you that you’re going to take a break.

Sometimes anger stems from difficulty asserting yourself. Learn to let people know—kindly and constructively—when they are upsetting you. Look for others who can support you when you are angry. And don’t forget to laugh—humor can be a great treatment for anger!

Exercise

When you work out, your body heats up quickly. There are two reasons for this. For one, contracting your muscles requires a chemical reaction, and not all of the energy produced to contract a muscle is actually used to pull that muscle. The rest of it escapes as body heat. The other reason we get hot when we exercise? Other chemical reactions, including your aerobic metabolism (what happens when your body burns fats, sugars, and proteins along with oxygen), and anaerobic metabolism (good for short bursts of physical energy).

Through this combination of reactions, we heat up fast as we put our bodies through the motions of exercise. All of that heat needs to escape lest we dangerously overheat. Once again, sweat comes to the rescue, providing our bodies a consistent cool to keep us moving.

People tend to get sweaty when they work out hard. To avoid dehydration, be sure that you are replenishing your body with plenty of water.

Stress and Anxiety

Just like when you get angry, stress triggers your “fight or flight” response, which can make your skin suddenly moist. Some anxiety is inevitable, but when it becomes prolonged and even chronic, it’s time to take measures to reduce your anxiety.

One treatment for reducing anxiety involves mindful relaxation. To apply this treatment to your own life, set aside 20 uninterrupted minutes each day. Go to a quiet place (no TV!). Rest in a comfortable position, whether it’s in a bed, chair, or on the floor. Focus on your breathing, a repeated word, a prayer, or a sound that puts you in a relaxed mood. As stressful thoughts come into your mind, let them. Learn to let them pass in and out without becoming attached to your stressful thoughts. This treatment can help you ease the anxiety in your life to make it more manageable.

Fever and Other Disease

Sometimes sweating is a symptom of a larger health problem. People with fevers often begin excessive sweating as the fever breaks and their bodies begin to cool. Sweating can be a symptom of several other diseases as well, including angina (chest pain related to the heart), heart attacks, overactive thyroid (hyperthyroidism), diabetes, and infections. Sometimes night sweats are brought on by either infections such as HIV, or some types of cancer. If you’ve been excessively sweating and think it may be a problem, contact your doctor.

Hyperhidrosis (Too Much Sweating)

Excessive sweating is known as hyperhidrosis. Hyperhidrosis can happen to anyone who has a fever or is dealing with a bout of anxiety, but for some this condition is ongoing and chronic and seems to be unrelated to the usual factors that lead to sweating. Here is some information about hyperhidrosis and what you can do about it.

Symptoms of Hyperhidrosis

If an area of your skin—usually the soles of the feet, palms of the hands, underarms or groin—is experiencing hyperhidrosis, the skin usually becomes pink or white. In really bad cases, the affected area of skin may become scaly, soft, or cracked.

Treatment for Hyperhidrosis

Sometimes the best treatment for hyperhidrosis is a strong, prescription-strength antiperspirant. Excessive sweating can also be treated with a methenamine solution. This solution generates small amounts of formaldehyde, a powerful astringent, which works to stop skin from sweating without the overwhelming smell of full-on formaldehyde.

There are many other medical treatments that may be used for hyperhidrosis based on the circumstances of the patient. These may include oral medicines, surgery on the nerves that lead to the sweat glands, injections of botulinum toxin, and psychological counseling to reduce anxiety.

Coffee and Other Caffeine Sources

Caffeine is a stimulant. It stimulates your central nervous system—essentially the brain and spinal cord. It does this by triggering the release of adrenaline. Coffee is one of the greatest sources of caffeine and plenty of people enjoy it every day. Because caffeine stimulates the nervous system, it also brings on that “fight or flight” response we talked about earlier.

As you know by now, when the body is excited—be it by anger, stress, or in this case caffeine—excessive sweating is likely to follow. If this is becoming a problem for you, consider cutting back on your morning cup.

Spicy Foods

It’s calling your name. Maybe it’s the jalapeños steeping their fiery oils into a bowl of spicy pho, or perhaps it’s a five-alarm chili. But whatever the spicy food may be, are you prepared for the sweating that will come with it?

Spicy food tricks your body, making it think it is hotter than it really is. That means sweaty skin. So a few chili peppers in your burrito may not be the best idea on a date or just before a job interview.

Menopause

Menopause plays a little trick on your hypothalamus. The hypothalamus is embedded deep inside the brain. It does several things, but one of the hypothalamus’ most important functions is controlling your body temperature. When you’re too cold, it’s the hypothalamus that tells your muscles to shiver. And when you’re too hot? You guessed it.

Sweating is the natural result of hot flashes during the time around the menopause. About 80% of menopausal women will experience them. Dropping estrogen levels throw the body’s temperature regulation out of whack. Symptoms include becoming flushed and sweaty. Treatment has typically been estrogen hormone therapy, but that has some side effects that need to be considered first. Other treatments include the use of antidepressants.

Drinking Too Much

When you drink, whatever extra alcohol that can’t be processed by your kidneys accumulates in the bloodstream. Alcohol enlarges the blood vessels near the surface of your skin, and this leads to sweating. When you experience excessive sweating after drinking just a little alcohol, you may have an intolerance. Withdrawing from alcohol addiction can also lead to sweating.

Smoking Cigarettes

This may not be the most important reason to quit smoking, but go ahead and add it to the list: smoking makes you sweaty. When you smoke, the nicotine releases acetylcholine, a chemical that leads to sweaty episodes. Smoking also raises your body temperature, which also contributes to sweating. Just like alcohol, when you kick smoking, you tend to perspire more heavily as well. But a little sweatiness is nothing compared to the health benefits, which include the prospect of a longer, healthier life.

Side Effect of Medications

Some medicine designed to improve your health can also make you sweaty. If you notice your skin growing extra damp after starting a new medication, consider whether you’ve been taking one of the following:

Versions of the medications above have been linked to increased perspiration.

Falling in Love

Does your special someone make you weak in the knees? Give you butterflies in the stomach? Make your heart beat faster? Perhaps it’s less romantic, but love makes you sweaty, too. Blame the rush of chemicals, similar to adrenaline, that accompany falling in love.

Being Pregnant

Whether it’s hot flashes while you’re awake or night sweats (nocturnal hyperhidrosis) as you sleep, pregnancy can be a sweaty affair. Although it may have many causes, nocturnal hyperhidrosis is one early sign of pregnancy. It can leave your sheets soaked as early as two weeks into a pregnancy, although it does not occur in all pregnant women.

The culprit is estrogen. As in the case of menopause, fluctuations in estrogen can cause sweaty problems for pregnant women. To stay cool in the evenings, wear light, natural fabrics, consider sleeping with a window open, and be sure to drink cool water when you are thirsty to avoid dehydration.

THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the eMedicineHealth Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.